Nutrient supply from grazed upland sward for weaned lambs in the autum

Abstract

Lamb finishing experiments conducted between 1983 and 1988 provided the opportunity to examine genotype difference in seasonal cycles of voluntary food intake. Diets, experimental conditions ages and previous treatments of lams were consistent between years. Constructed male lambs of six genotype were offered ad-libitum, a straw-based complete pelleted diet. The rates at which absolute VFI increased from the autumn through to May varied between genotypes in associated with their absolute growth rates. In mid-February, the mid point of the experiments there was significant heterogeneity in both absolute intake and intake per kg BW. Scottish Blackface lambs had a strong seasonal depression in VFI around the end of November. The Suffolk x (Border Leicester x Blackface Lambs) and Suffolk x (East Friesland x Blackface Lambs) both had a slight seasonal depression in VFI whereas Suffolk x (East Friesland x North Country Cheviot), Beulah and Welsh Mountain lambs showed no such depression. Further work will investigate the relationship betwen the seasonal pattern in different genotypes of VFI and growth, performance and carcase composition.